Post top luminaire

ABSTRACT

A luninaire adapted to be mounted at the top of a post and to direct light below a horizontal plane is disclosed. A housing element preferably of a polycarbonate material comprises a housing for an electrical system and a refractor means having an interior and exterior prismatic structure.

BACKGROUND OF THE INVENTION

This invention relates to a luminaire adapted to be mounted at the topof a post and to project or to direct light below a horizontal plane.More particularly, this invention is directed to a luminaire having anew and improved refractor structure adapted for outdoor use.

The present invention is specifically directed to use in an outdoorenvironment where efficient illumination, durability and resistance tovandalism are important considerations. The invention also provides anew and improved luminaire which is aestheticly attractive andrelatively easy to maintain.

A number of prior art luminaires have incorporated prismatic structuresto facilitate the directing and distribution of light from theluminaire. U.S. Pat. Nos. 31,353; 31,149,747 and 3,344,268 all generallydisclose the concept of employing a multiplicity of prisms in the formof vertical or horizontal rib structure to distribute or direct thelight from a luminaire. U.S. Pat. No. 3,395,273, discloses a street lampluminaire comprising a plurality of prisms for directing light below thehorizontal plane of the luminaire. The present invention is directed toproviding a series of prismatic structures at both the exterior andinterior of a refracting portion of an element having a uniqueintegrated structure adapted to accomplish a number of additionalobjectives as will be pointed out below.

The use of a polycarbonate material in a refracting element for a streetlight luminaire is disclosed in U.S. Pat. No. 3,661,685. The presentinvention is a new and improved luminaire which employs the propertiesof polycarbonates not only to provide a refracting element havingefficient optical qualities, but also to provide a durable elementadapted for use in an outdoor environment.

SUMMARY OF THE INVENTION

The new and improved luminaire comprises a base having a means formounting the luminaire at the top of a post and generally supporting anelectrical system for a lamp. A polycarbonate housing, which is of asubstantially cylindrical shape and having a substantially H-shapedcross-section, is received on the base plate. The housing functions toprovide both a refracting component for the lamp and to provide therequired isolation of the electrical circuit components associated withthe lamp.

The housing is further provided with a series of longitudinally arrangedprisms on the interior of the refracting portion, as well as a series ofcircumferentially extending prisms on the exterior of the refractingportion. The prisms on the exterior of the refracting portion arepreferably structured and positioned according to specific parameters sothat the light may be efficiently directed and distributed below ahorizontal plane defined by the luminaire.

The new and improved luminaire also comprises a housing which may beprovided with an opaque portion to conceal the electrical system.Additional means may be provided to conceal the exterior supportstructures and increase the resistance of the luminaire structure toenvironmental elements and vandalism.

An object of the invention is to provide a new and improved luminairewhich is adapted to be mounted at the top of a post and to direct lightbelow a horizontal plane.

An object of the invention is to provide a new and improved luminairewhich is durable and adapted to be resistant to vandalism.

An object of the invention is to provide a new and improved luminairewhich is relatively easy to install and maintain.

An object of the invention is to provide a new and improved luminairewhich has an efficient optical performance specifically suited to publicuse in an outdoor environment.

Other objects and advantages of the invention will become apparent fromthe accompanying drawings and the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of the luminaire mounted on the top of a post,the side and rear views of the luminaire being substantially identical;

FIG. 2 is an interior view of the luminaire of FIG. 1, the externalportion being broken away along a central vertical plane.

FIG. 3 is a top plan view, partly in schematic form, illustrating alower portion of the luminaire of FIG. 2;

FIGS. 4-7 are each enlarged fragmentary sectional views of the upperside portion of the luminaire of FIG. 2; and

FIG. 8 is a sectional view taken along the line 8--8 of FIG. 7.

DETAILED DESCRIPTION

With reference to FIG. 1, the luminaire 10 is illustrated in itspreferred position mounted at the top of a post P in an outdoorenvironment. The external structure of the luminaire 10 is substantiallysymmetrical about a central vertical axis, and thus FIG. 1 illustratesthe exterior of the luminaire 10 as viewed from substantially anyperipheral position relative to the luminaire in the horizontal planethereof. From an external perspective, luminaire 10 generally comprisesa fixture base 12 supporting a housing element 13 comprising anelectrical housing 14 and a lens cover 16. A cover plate 18 encloses thelens cover 16.

With reference to FIG. 2, housing element 13 generally comprises acylindrical structure having a circumferential recessed portion 20 and asubstantially H-shaped cross-section. An integral central interior panel22 positioned proximate recessed portion 20 generally defines theboundary between lens cover 16 and electrical housing 14. Panel 22functions in part as an electrical insulator to form the top of theelectrical housing 14 for the luminaire electrical system which will bedescribed below. Panel 22 further comprises a central lamp aperture 24as well as a pair of rod apertures 26 and 28, the function of which willbe described below.

Housing element 13 is preferably made of a polycarbonate material of adurable and rugged quality which is impervious to high impact andpossesses a resilience which allows housing element 13 to withstandintense abuse. The structural configuration proximate the intersectionof panel 22 with the recessed portion 20 intermediate lens cover 16 andelectrical housing 14 acts to provide for a resilient structure in theH-shaped housing element 13. An important feature of housing element 13is the ability of the element to withstand abuse and vandalism since theusual environment of the invention is an outdoor public use area.

Fixture base 12 is structured to receive the lower portion of housingelement 13. A rabbet 30 may be provided on base 12 to facilitate thereception of the housing element 13 onto the fixture base 12. A mountingmeans shown generally as 32 is centrally provided in fixture base 12 tofacilitate the mounting of the luminaire at the top of a post. Apreferred means for mounting luminaire 10 is in conjunction with a posthaving a post tenon (not shown) which can be received and secured intenon aperture 34 defined by a tapered cylindrical wall 36. Thisarrangement assures the alignment of the luminaire with the post andaccommodates manufacturing tolerances. A lower fixture portion 38 mayrest on the top of the post proximate the tenon extension. In preferredform the fixture base and mounting means cooperate with the top of thepost in such a manner that the post and fixture base appear to form anintegral structure having a smooth surface continuum with a minimaldegree of discontinuity between the post and the luminaire so that theexternal appearance does not present a ready clue as to how theluminaire may be dismounted or disassembled.

Fixture base 12 also provides a support structure for the electricalsystem and the lamp. With reference to FIG. 3, starter 40 is secured tothe top of the fixture base by conventional means such as screws 42.Capacitor 44 is secured to fixture base 12 by capacitor strap 46.Ballast 48 is secured to mounting means 32 of fixture base 12 by meansof a ballast mounting strap 50. A wiring diagram 52 may also be affixedto the fixture base 12. In preferred form, lamp base 56 is positionedabove mounting means 32. Lamp 58 is received in base 56. It is of courseunderstood that the foregoing starter 40, capacitor 44, ballast 50, andlamp 58 are electrically connected, and are representative of a numberof electrical lamp systems that may be employed in connection with theluminaire. It is to be understood that the electrical lamp system maytake a variety of forms and the electrical components illustrated hereinare a preferred embodiment and not a limitation as to the application orscope of the invention.

A pair of support brackets 60 and 62 adapted to receive the ends of thefastener rods 64 and 66 extend upwardly from fixture base 12. Whenproperly positioned, rod recesses 26 and 28 of the panel 22 align withbrackets 60 and 62 so that fastener rods 64 and 66 may be threadablyreceived in brackets 60 and 62 to secure panel 22 and hence housingelement 13 to the fixture base 12.

Cover plate 18 comprises a rabbet 67 which engages with the top ofhousing element 13 and a pair of recessed portions 68 and 70, eachhaving apertures 72 and 74 which align with fastener rods 64 and 66 toreceive upper rod ends opposite the ends received in brackets 60 and 62.A pair of nuts 76, which may be tightened to secure cover plate 18against the top of the lens cover 16 of housing element 13 arepreferably received in recessed portions 68 and 70 so that the nuts 76are not readily visible from ground or street level.

With reference to FIGS. 4-7, the exterior of the lens cover 16 isprovided with a plurality of parallel prisms protruding outwardly andcircumferentially around the exterior of the housing element 13. Eachprism is defined by intersecting upper and lower surfaces. The prismsfunction to direct and distribute the light generated by the lamp belowthe horizontal plane of the luminaire. With further reference to FIG. 4,the successive adjacent prisms from top to bottom are designated P₁, P₂,P₃ , . . . , P_(m). The distances between successive adjacent prismswhich may be defined as the vertical distances between the intersectionof the upper and lower surfaces, are designated D₁, D₂,D₃, . . . ,D_(m-1).

The angles of protrustion designated A₁, A₂, A₃, A₄, . . . A_(m) aredefined as the angles that the upper surfaces of each prism P₁, P₂, P₃,P₄, . . . P_(m) makes with the horizontal. As can be ascertained fromFIGS. 4-7, the sequence of the angles of protrusion A₁, A₂, A₃, A₄, . .. A_(m) is given by the relationship:

    A.sub.n ≦A.sub.n+1.

In a preferred embodiment, the angles of protrustion A₁, A₂, A₃, A₄, . .. A_(m), increase sequentially from approximately 39 degrees toapproximately 87 degrees. The angles of elevation relative to thehorizontal of the lower surfaces are acute angles of magnitudessubstantially less than 45 degrees.

With further reference to FIGS. 4-7, the distances between adjacentprisms may be divided into four groups designated G₁, G₂, G₃, and G₄.Within each group the distance D_(n) between successive adjacent prismsis contsant. In a preferred embodiment, the distances D₁, D₂, D₃, . . .D_(m-1), satisfy the following relationship:

    D.sub.n ≧D.sub.n+1,

where D₁,D₂,D₃ . . . D_(m-1) are the distances between successiveadjacent prisms P₁,P₂,P₃, P₄, . . . , P_(m). In addition, therelationships between the constant distances between adjacent prisms ofeach of the groups is defined by the following relationship:

    D.sub.II =2D.sub.I

    DIII=3D.sub.I

    D.sub.IV =4D.sub.I

where D_(I) is the constant distance between adjacent prisms in thefirst group, D_(II) is the constant distance between adjacent prisms inthe second group, D_(III) is the constant distance between adjacentprisms in the third group, and D_(IV) is the constant distance betweenadjacent prisms in the fourth group.

With reference to FIG. 8, a plurality of parallel prisms protrudes fromlens cover 16 into the interior of housing element 13. The prisms whichextend into the interior are designated generally as Q_(I), Q₂, Q₃, Q₄,. . . The latter prisms in preferred form are defined by pairs ofintersecting surfaces substantially equally spaced around the interiorcircumference of lens cover 16 and extending longitudinally in avertical direction from the top of the lens cover 16 proximate housingcover 18 to proximate the recessed portion 20. In preferred form, thefaces of prisms Q_(I), Q₂, Q₃, Q₄, . . . are congruent and intersect atsubstantially 90 degree angles.

The series of prisms protruding from the exterior of the lens cover 16,together with the series of prisms protruding into the interior of lenscover 16, provide a soft evenly distributed light which is directeddownwardly in an efficient manner from the horizontal plane of theluminaire. The luminaire during daylight hours, by virtue of theexterior series of prisms, presents the appearance of a fine crystallinecut glass structure. The prisms also function to prevent the luminaireinterior from being externally visible.

Housing element 13, which integrates into a single element the lenscover and electrical system cover, acts to provide a luminaire which isrelatively easy to install and maintain. The luminaire may be installedby first mounting the fixture base on a post tenon. The electricalsystem of the luminaire is connected to wires extending preferablythrough the center of the post. Housing element 13 is secured to thefixture base, by aligning the recesses 26 and 28 of panel 22 of thehousing with the support brackets 60 and 62, engaging fastener rods 64and 66 into the brackets and securing cover plate 18 to the top ofhousing element 13 by bolting nuts 76 to the top of the fastener rods.

Because of the polycarbonate material used in the housing, the luminairewill be relatively indestructable and is adapted to withstandintentional abuse as well as the adverse effects caused by atmosphericconditions and weather.

An important design feature of a preferred embodiment of the luminaireis the provision whereby the luminaire structure is adapted to hidevarious connecting elements which, if easily visible, could be theinitial impetus to vandalism and unauthorized access to the luminaire.In a preferred form, an opaque material is applied to the insidesurfaces of the sides of the electrical housing 14 so that the bottomportion of the luminaire appears to be a base which receives a removablelight refracting globe. In addition, the color of the electrical housingcan be made to match the color of the fixture base and for that matterthe color of the post so that it is difficult to ascertain from groundlevel or street level that the electrical housing, fixture base and poleare separate components.

An additional feature is that by essentially securing the luminaire atthe top by tightening the nuts 76 so that they are received in therecessed portions 68 and 70 of the cover place 18, it is difficult forone unfamiliar with the luminaire to determine how to remove the lenscover or change the lamp bulb. It is, of course, also apparent thatauthorized access to the lamp bulb can be easily obtained by merelyloosening the nuts 76 and removing the cover plate 18. The integralstructure of housing element 13 obviates the necessity to remove thelens cover or align same with the base as required with conventionalglobe/base light fixtures.

It may thus be seen that the objects of the invention set forth, as wellas those made apparent from the foregoing desription, are efficientlyobtained. While preferred embodiments of the invention have been setforth for purposes of disclosure, modifications of the disclosedembodiments of the invention as well as other embodiments thereof mayoccur to those skilled in the art. Accordingly, the appended claims areintended to cover all embodiments of the invention which do not departfrom the spirit and scope of the invention.

What is claimed is:
 1. A luminaire adapted to be mounted at the top of apost and to direct light below a horizontal plane, said luminairecomprising:a base having a mounting means for mounting said luminaireabove an area to be lighted: an electrical means positioned on said baseto operate a lamp; a unitary housing element received on said base, saidhousing element having upper and lower portions of generally cylindricalshape with an intermediate interior insulator panel intersecting thehousing element sides to form a substantially H-shaped crosssection, thelower cylindrical portion enclosing said electrical means and the uppercylindrical portion forming a light refractor means for said lamp, thelight refractor means comprising an interior longitudinally disposedprism means and exterior prism means adapted to direct light below thehorizontal plane defined by the top of the unitary housing element; anda cover enclosing the top of said housing element.
 2. A unitary lenscover for a luminaire of a type having an electrical means to operate alamp and adapted to direct light below a horizontal plane, said lenscover comprising upper and lower portions of generally cylindricalshapes with an intermediate insulator panel intersecting the cover sidesto form a substantially H-shaped cross-section, said upper portionhaving a light refracting means comprising an interior longitudinallydisposed prism means and an exterior prism means adapted to direct lightbelow the horizontal plane defined by the top of lens cover.
 3. Theluminaire of claim 1 wherein said housing element further comprises acircumferential recessed portion proximate the intersection of theinterior panel with the sides.
 4. The luminaire of claim 1 wherein saidrefractor means comprises a plurality of parallel prisms extendinglongitudinally at the interior of said housing.
 5. The luminaire ofclaim 4 wherein said refractor means further comprises a series ofsuccessive adjacent parallel prisms circumferentially protruding at theexterior of said housing, said series of prisms being designated P₁,P₂,P₃, P₄ . . . , P_(m), P₁ being the prism nearest the cover.
 6. Theluminaire of claim 5 wherein angles of protrusion A₁, A₂, A₃, A₄, . . .A_(m) of the corresponding prisms P₁, P₂, P₃,P₄, . . . P_(m) satisfy therelationship:

    A.sub.N ≧A.sub.N+1 ;

where A₁, A₂, A₃, A₄, . . . A_(m) are the corresponding angles ofprotrusions of prisms P₁, P₂, P₃, P₄, . . . P_(m) relative to thehorizontal.
 7. The luminaire of claim 5 wherein the correspondingdistances D₁, D₂, D₃, . . . , D_(m-1) . . . between prisms P1, P2, P3,P4 . . . satisfty the relationship:

    D.sub.n ≦D.sub.n+1;

where D₁, D₂, D₃, . . . D_(m-1) are the distances between successiveprisms P₁, P₂, P₃, P₄, . . . P_(m).
 8. The luminaire of claim 3 whereinthe housing element portion proximate said recessed portion isresilient.
 9. The luminaire of claim 1 further comprising a faster meansto secure the cover, said fastener means adapted to be concealed. 10.The luminaire of claim 9 wherein said fastener means further comprises apair of rods extending from said base plate and adapted to be receivedand secured in recessed portions of said cover plate.
 11. The luminaireof claim 1 wherein said housing element is made of polycarbonate. 12.The luminaire of claim 1 wherein said mounting means further comprises acentral aperture adapted to receive a post tenon.
 13. The luminaire ofclaim 1 wherein the interior surface of said lower cylindrical portionis opaque.
 14. The lens cover of claim 2 wherein said cover is made ofpolycarbonate.
 15. The lens cover of claim 2 further comprising aresilient portion proximate the periphery of the interior panel.
 16. Thelens cover of claim 2 wherein the interior of said lower cylindricalportion is opaque.
 17. The lens cover of claim 2 wherein said panel hasa central aperture.
 18. The lens cover of claim 2 wherein said interiorprism means comprises a plurality of prisms longitudinally positionedand extending into the interior of the refractor portion.
 19. The lenscover of claim 2 wherein the exterior prism means comprises a series ofadjacent parallel prisms extending circumferentially around theexterior.
 20. The lens cover of claim 19 wherein the distance betweensuccessive adjacent prisms from the top of the lens cover to the bottomdoes not decrease.
 21. The lens cover of claim 2 wherein the prismsextend at angles to the horizontal such that the angle of protrusion foreach succeeding prism from the top to the bottom is greater or equal tothe corresponding angle of protrusion of the preceding prism.
 22. Thelens cover of claim 18 wherein the interior prism means comprise prismshaving substantially congruent faces intersecting at substantially 90degrees.
 23. The lens cover of claim 19 wherein the series of prismscomprises four groups, each group having a constant distance betweenadjacent prisms D_(I), D_(II), D_(III), and D_(IV), satisfying therelationship:

    D.sub.II =2D.sub.I

    D.sub.III =3D.sub.I

    D.sub.IV= 4D.sub.I

where D_(I) is the constant distance between adjacent prisms in thefirst group, D_(II) is the constant distance between adjacent prisms inthe second group, D_(III) is the constant distance between adjacentprisms in the third group, and D_(IV) is the constant distance betweenadjacent prisms in the fourth group.